the immune system dr. jena hamra. immune system 3 major functions protects body from disease ...
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The Immune SystemThe Immune System
Dr. Jena Hamra
Immune SystemImmune System
3 major functions Protects body from disease
Bacteria, viruses, fungi, parasites ANTIGEN: Anything that causes immune response
Remove dead or damaged tissue Recognizes and removes abnormal cells
2 types of immune responses Innate immunity
Nonspecific, immediate Acquired immunity
Specific, can take several days
Anatomy of the Immune SystemAnatomy of the Immune System
Lymphoid tissuesPrimary
Bone marrowThymus gland
SecondarySpleenLymph nodesDiffuse tissues
• Tonsils• GALT
Cells of the Immune SystemCells of the Immune System
LeukocytesEosinophilsBasophils/Mast cellsNeutrophilsMonocytes/MacrophagesLymphocytesDendritic cells
Cell FunctionCell FunctionGRANULOCYTESEosinophils
Fight parasitesAllergic reactions
BasophilsRelease histamine, heparin
NeutrophilsIngest and digest bacteriaMost abundant WBC in bloodRelease pyrogens, mediators of inflammation
Cell FunctionCell Function Lymphocytes
Secrete antibodies Memory cells Cytotoxic cells
Monocytes Macrophages in tissue Primary scavengers
Bacteria, tissue Antigen presenting cells
Dendritic cells Recognize, capture antigen Antigen presenting cells
Innate ImmunityInnate Immunity
Nonspecific responsePhysical barriers
SkinMucous membranesCiliated epithelium
PhagocytesMacrophages and neutrophilsPhagocytosis
Receptor mediatedExtravasation and diapedesis
Chemical MediatorsChemical Mediators
InflammationCytokines from macrophages
ChemotaxisIncrease capillary permeabilityFever
Acute phase proteinsProduced by liverReleased early in immune responseOpsonins, antiprotease
Chemical MediatorsChemical Mediators Histamine
Located in granules of mast cells and basophils Initiates inflammatory response
Increase capillary permeability• Edema
Vasodilation• Increased local blood flow
Interleukins Interleukin-1
Secreted by activated macrophages Increase capillary permeability Stimulates acute phase protein synthesis Induces fever Stimulates cytokine release
Chemical MediatorsChemical Mediators
BradykininVasodilatorStimulates pain receptors
Complement proteinsCascadeFormation of membrane attack complex
Lipid soluble moleculesInsert into pathogen membrane, form pores
• Cell lysis
Acquired ImmunityAcquired Immunity
Selective reaction to a specific antigenMediated by lymphocytes
Membrane receptors specific for particular ligand
Same specificity = clonesClonal expansion
First exposure to antigenCells divide = new clonesProduces effector cells and memory cells
Second exposure to antigenActivation of memory cells
Lymphocyte CytokinesLymphocyte Cytokines
Required for activation and normal immune response
InterleukinsClonal expansion and differentiation
InterferonsAlpha and beta: activate pathways against viral
infectionGamma: Activates macrophages
Lymphocyte SubtypesLymphocyte Subtypes
B lymphocytesSecrete antibodies
T lymphocytesHelper T cells (CD4): Secrete cytokines
required for development of immune responseCytotoxic T cells (CD8): Attack and destroy
foreign cellsNatural killer cells: Attack and destroy virally
infected or cancer cells
Antibody Secretion Antibody Secretion (Humoral Immunity(Humoral Immunity
B cellsActivated B cells Plasma cells
Plasma cells secrete antibodiesPrimary and secondary antibody response
Primary: Slower and and weakerIgM
Secondary: Faster, more antibodies producedIgG
AntibodiesAntibodies
IgG 75%, Secondary response
IgM Primary antibody response
IgA Secretory: saliva, tears
IgE Allergic responses
IgD Cell surface receptor on B lymphocytes
Antibody StructureAntibody StructureY shaped proteins
2 heavy chains, 2 light chainsFab region: antigen binding sites
Antibody FunctionAntibody Function
Opsonins Coat antigens, facilitate phagocytosis
Make antigens clump Activate other immune cells
Cytotoxic T cells Phagocytic cells B lymphocytes
Activate complement Activate mast cells
Cellular ImmunityCellular Immunity T lymphocytes
Mature in thymus Require antigen presenting cells Cytotoxic T cells Helper T cells
T cell receptor Required for recognition of antigen
Major histocompatibility complexes Required for antigen presentation CD4 recognize MHC II CD8 recognize MHC I
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